Incandescent lamp



F 24 1970 LEROY s. HUSTON, JR 3,497,753

' INCANDESCENT LAMP Filed Oct. 31, 1967 F|G.I FIG. 2

LEROY S. HUSTON JR.

INVENTOR BY TTORNEY United States Patent 3,497,753 INCANDESCENT LAMP Leroy S. Huston, .lr., Beverly, Mass, assignor to Sylvania Electric Products, Inc., a corporation of Delaware Filed Oct. 31, 1967, Ser. No. 683,755 Int. Cl. H013 1/88, 19/42 US. Cl. 313271 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention pertains to incandescent lamps and particularly to single ended tubular quartz halogen lamps in which a quantity of halogen has a regenerative effect and improves lamp maintenance. More specifically, it relates to a connection of a filament to a lead-in wire which supports the filament coaxially within the envelope.

Description of the prior art The prior art showed small quartz halogen lamps in which lead-in wires were supported only by a seal at the base of the lamp. As lamp sizes increased, it became necessary to provide additional support for the lead-in wires and filaments, especially in lamps where the filament was mounted coaxially within the lamp envelope. In some of these lamps, the end of a lead-in wire was positioned within the residual fused tip of the exhaust tube and the filament leg was directly connected thereto. This construction was satisfactory for lower wattage lamps, but in higher wattage lamps the fused tip would overheat and could lead to premature failure. If the distance between the filament and the envelope tip were increased by, for example, increasing the length of the filament leg, the resultant construction would be generally too weak to maintain the filament in coaxial alignment for the life of the lamp. In addition, in those filaments in which the filament body, leg and coil were machine Wound from an integral piece of wire, there was a practical limit imposed by the coiling equipment to the length of the leg that could be produced and to the diameter of the coil at the end of the filament leg. Where connection was established by inserting the end of the lead-in wire into the coil at the end of the filament leg, the diameter of the lead-in wire that could be used was limited to the inside diameter of the coil. This could result in the use of a leadin wire that did not have sufficient rigidity to maintain the filament in a position that was substantially coaxial and stable throughout the useful life of the lamp.

It is an object of this invention to provide a lamp having an improved filament support and which permits a greater flexibility in the longitudinal positioning of a coaxial filament.

SUMMARY This invention discloses a quartz halogen lamp with an improved filament mount which has a refractory metal connector supporting the filament and making electrical connection thereto. The connector is roughly U- 3,497,753 Patented Feb. 24, 1970 ice shaped and has a coil at one end. At the other end, the connector has an arm, projecting toward the coil but spaced therefrom, which is in substantial alignment with the axis of the coil.

A lead-in wire extends within the lamp envelope and terminates within the exhaust tube ripoff which is centrally located at the end of the lamp. The connector coil encircles the terminus of the lead-in wire and is supported thereon. The arm at the other end of the connector is inserted in, and supports, a coil at the end of the filament leg.

The opposite leg of the filament has a similar coil, which is directly supported on the coaxially positioned end of a shorter lead-in wire.

The connector and lead-in wires are made of heavier wire than the filament and have sufficient physical rigidity to maintain the filament substantially coaxial throughout the life of the lamp. In addition, because of the connector, the diameter of the lead-in wire that can be used is not limited to the diameter of the coil at the end of the filament leg.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a front elevational view of a lamp in accordance with this invention.

FIGURE 2 is a side elevational view of the same lamp.

DESCRIPTION OF THE PREFERRED EMBODIMENT A quartz halogen lamp, as shown in FIGURES 1 and 2, comprises a tubular quartz envelope 1 having press seal 2 at one end thereof and a centrally positioned exhaust tube tipoff 3 at the opposite end. Lead-in wires 4 and 5 are supported in press seal 2 and extend interiorly into envelope 1 through a supporting quartz rod 16. Longer lead-in wire 4 is adjacent to, but spaced from, envelope 1 and terminates within tipoff 3, which is centered on the end of envelope 1. Shorter lead-in wire 5 extends only into the lower section of the lamp and has several bends that position its end coaxially, pointed toward the base.

Connector 6 is roughly U-shaped and is made from a single length of refractory metal wire. At one end of connector 6 is coil 7 which is annularly disposed on terminus 8 of lead-in wire 4 by slipfitting thereon. Coil 7 is subsequently hot crimped to establish a positive physical and electrical connection to terminus 8. The opposite end of connector 6 has a right angle bend forming a short projecting arm 9 substantially in alignment with, and pointing toward, coil 7.

Filament 12 integrally comprises legs 11 and 13 having coils 10 and 14 at their respective ends. Upper coil 10 is supported and electrically connected to arm 9 by slipfitting thereon and subsequently hot crimping. Lower coil 14 is similarly atached to the coaxial end of shorter lead-in wire 5. Filament 12 must be stretched slightly, when it is thus mounted, to keep it under slight tension, the purpose of which is to prevent sagging and maintain coaxial alignment for substantially the useful life of the lamp.

Connector 6 improves the support of the filament, when compared with filaments having a long leg attached directly to the upper lead-in wire within the tipoff, since it is made of heavier wire than is the filament leg. At the high temperatures, usually over 2200 C., at which lamps of this type operate, the filament and lead-in wires can distort, embrittle and-sag. By reducing the span which the weaker filament leg must traverse and connecting it to a stronger connector, the possibility of the filament distorting from its coaxial alignment during life is materially reduced.

In addition, the use of connector 6 permits greater flexibility in the design and construction of single-ended quartz halogen lamps. For example, when a slight design change in the wattage of a lamp necessitates a change in the filament length, only a change in the length of connector 6 would be required to accommodate the dilferent length of the filament. The envelope and the mounting bridge, which comprises lead-in wires, support wires and quartz rod, would not have to be modified.

In a specific example for a 2000 watt lamp in accordance with this invention, envelope 1 was 1 inch diameter by 4% inches long overall and press seal 2 was 1% inches long. Lead-in wires 4 and 5 were made of 35 mil tungsten wire and were sealed in press seal 2, where they were connected to the usual molybdenum foil ribbons. Lead-in wires 4 and 5 supported quartz rod 16 which was located about inch above press seal 2. Terminus 8 of longer lead-in wire 4 was about 4 inch long, of which about half protruded into tipofi 3.

Connector 6 was made of 28 mil wire and, excluding coil 7 and arm 9, was substantially U-shaped, the length of each of its three sides being about inch. Coil 7 protruded substantially orthogonally from the end of one of the open sides in a direction opposite that of the opposing side of the U. Coil 7 consisted of 6. turns wound at 100% pitch and had an inside diameter of 36 mils. Arm 9 was about A; inch long and protruded from the end of the opposite arm in a direction towards coil 7.

The combination of lead-in wires 4 and 5, quartz rod 16 and connector 6 constituted a bridge which provided a physically stable network for mounting filament 12 thereon and subsequently inserting into envelope 1 during the manufacturing operation. Quartz rod 16 was about inch long by inch diameter and lead-in wires 4 and 5 were partially embedded therein by hot pressing. An additional tungsten wire 15, 18 mils in diameter, was also embedded in quartz rod 16 to provide a support for the midpoint of filament 12. As mentioned previously, connector 6 was attached to lead-in wire 4 by inserting terminus 8 into coil 7 and hot crimping the latter thereon. The filament mounting space between arm 9 and the downward projecting coaxial end of lead-in wire 5 was about 1% inches.

Filament 12 was a coiled coil made of 14 mil tungsten wire, and had a body about 1 inch long by inch diameter. Legs 11 and 13 consisted of uncoiled sections about inch long and, along with coils and 14 at their respective ends, were substantially coaxial with the body of filament 12. Coils 10 and 14 consisted of 4 turns each and had an inside diameter of 29 mils. The mounting length of filament 12, which excludes coils 10 and 14, was thus 1 /2 inches, necessitating a stretch of A1, inch when the filament was mounted on the bridge. After mounting, coils 10 and 14 were hot crimped to further secure their mechanical and electrical connection.

At final assembly, the bridge, with filament 12 thereon, was inserted into the open end of envelope 1, and terminus 8, with coil 7 thereon, was positioned in the centrally located exhaust tube which had a diameter of about 6 millimeters, at the opposite end of the envelope. After press sealing and introduction of a bromine-nitrogen atmosphere into the envelope, the exhaust tube was tipped oif at a point beyond the extension of terminus 8.

It is apparent that modifications and changes can be made within the spirit and scope of the invention, but it is our intention however only to be limited by the spirit and scope of the appended claims.

I claim:

1. A quartz halogen lamp comprising:

a tubular envelope press sealed at one end and having a substantially centered exhaust tube tipoflf at the other;

a first lead-in wire extending from said press seal and disposed in said tipoff;

a connector having a fastening means at one end thereof, said fastening means being attached to said lead-in wire;

a second lead-in wire extending from said press seal into the interior of said envelope;

and a coaxial filament one end of which is connected to said second lead-in wire and the other end of which is connected to the other end of said connector.

2. The lamp of claim 1 wherein said fastening means comprises a coil which encircles said lead-in wire.

3. The lamp of claim 2 wherein said filament includes a coil at its end, said coil encircling said other end of said connector.

4. The lamp of claim 3 wherein said coils are hot crimped at the ends of said connector and said filament.

5. The lamp of claim 4 wherein said cinnector is formed from a single length of wire, the diameter of which is greater than the diameter of said filament wire.

6. A quartz halogen lamp comprising:

a tubular envelope having a press seal at one end and a substantially centered exhaust tube tipoff at the other;

a filament disposed substantially coaxially within said envelope;

a quartz rod disposed within said envelope substantially orthogonal to said filament between said filament and said press seal;

a first lead-in wire extending through said quartz rod and disposed in said tipoff;

an essentially U-shaped connector, the upper end of which is connected to said first lead-in wire and the lower end of which is connected to the upper end of said filament;

a second lead-in wire extending through said quartz rod and connected to the lower end of said filament.

7. The lamp of claim 6 wherein the upper end of said connector comprises a coil which encircles, and is hot crimped on, said first lead-in wire.

8. The lamp of claim 7 wherein the ends of said filament comprise coils which encircle, and are hot crimped on, the respective ends of said connector and second lead-in wire.

References Cited UNITED STATES PATENTS 3,403,280 9/1968 Cardwell 313271 RAYMOND F. HOSSPELD, Primary Examiner U.S. Cl. X.R. 

